Thin film thermal print head

Abstract

After the mesas are formed in the glass glaze over an aluminum oxide substrate by etching, and before resistive and conductive materials are deposited over the mesas by thin film techniques, an aluminum oxide underlayer is applied. The aluminum oxide underlayer provides controlled etching of the raised heater elements and conductors to prevent undesirable additional erosion of the glass glaze mesas.

I claim: 
     
       1. A thin film thermal print head comprising: an aluminum oxide substrate;   a layer of glass glaze covering the substrate having a plurality of mesas formed on the surface thereof;   a layer of etchant-resistant material covering the layer of glass glaze including the plurality of mesas and having a high chemical resistance to photoresist materials;   a layer of resistive material covering the etchant-resistant material in the area of the mesas to form resistive heater elements thereon;   a plurality of electrical conductors coupled to the heater elements for connecting electrical power thereto;   a layer of oxide of the resistive material covering each of heater elements; and   a layer of wear-resistant material covering the layer of oxide and having a relatively high thermal conductivity.   
     
     
       2. A thin film thermal print head as in claim 1 wherein the etchant-resistant material is aluminum oxide. 
     
     
       3. A thin film thermal print head as in claim 1 wherein the wear-resistant material is aluminum oxide. 
     
     
       4. A thin film thermal print head as in claim 1 wherein the etchant-resistant material and the wear-resistant material are aluminum oxide.